Cheapest return flights from Islip to San Juan in August from $300

Best time to book flights for Islip (ISP) to San Juan (SJU) flights at AirHint

AirHint found the following cheapest return flights from Islip (ISP) to San Juan (SJU) in August 2025 (see full year).

Return flights

21 Aug - 25 Aug Frontier Airlines
18 Aug - 25 Aug Frontier Airlines
18 Aug - 22 Aug Frontier Airlines
28 Aug - 02 Sep Frontier Airlines
28 Aug - 04 Sep Frontier Airlines
29 Aug - 02 Sep Frontier Airlines
29 Aug - 03 Sep Frontier Airlines
22 Aug - 24 Aug Frontier Airlines
19 Aug - 27 Aug Frontier Airlines
18 Aug - 27 Aug Frontier Airlines
21 Aug - 24 Aug Frontier Airlines
14 Aug - 19 Aug Frontier Airlines
14 Aug - 25 Aug Frontier Airlines
24 Aug - 27 Aug Frontier Airlines
29 Aug - 01 Sep Frontier Airlines
20 Aug - 02 Sep Frontier Airlines

Also check the deals for one-way flights from Islip to San Juan in August.

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The deals are updated regularly. The prices may go up as tickets are purchased by other travellers. Only the cheapest flights are offered. Select a price to book and secure these cheap prices.

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